Rj. Errington et al., BETA-DIKETONATE DERIVATIVES OF TITANIUM ALKOXIDES - X-RAY CRYSTAL-STRUCTURES AND SOLUTION DYNAMICS OF THE BINUCLEAR COMPLEXES [(TI(OR)(3)(DIK))(2)], Polyhedron, 17(5-6), 1998, pp. 659-674
The crystal structures of the 2,4-pentanedionato (acetylacetonato, aca
c) and 2,2,6,6-tetra-methylheptane-3,5-dionato (tmhd) compounds (tmhd)
compounds [{Ti(OR)(3)(dik)}(2)] (dik = acad, R = Me, Et, Pr-i; dik =
tmhd, R = Me, Pr-n, Pr-i), obtained from reactions between Ti(OR)(4) a
nd one equivalent of dikH, have been determined for the first time. In
the solid state? these compounds adopt centrosymmetric, alkoxide-brid
ged binuclear structures which in solution undergo ligand redistributi
on to give mixtures of [{Ti(OR)(3)(dik)}(2)], [Ti(OR)(2) (dik)(2)] and
Ti(OR)(4). When R = Pr-i, the equilibrium favours the mononuclear com
pounds, whereas when R = Me, Et or Pr-n the binuclear compounds can be
observed in the H-1 NMR spectra. Variable-temperature H-1 NMR spectra
provide an insight into the dynamic behaviour of the methoxides [{Ti(
OMe)(3)(dik)}(2)], and possible ligand exchange mechanisms are discuss
ed. No conclusive evidence was obtained for the existence of dimeric o
r monomeric [Ti(OBut)(3)(dik)] in the solid state or in solution. (C)
1998 Elsevier Science Ltd. All rights reserved.